Desk having elevatable storage cabinet



April 1966 A. R. BARTLETT 3,245,741

DESK HAVING ELEVATABLE STORAGE CABINET Filed Aug. 20, 1964 5Sheets-Sheet 1 .April 12, 1966 A. R. BARTLETT DESK HAVING ELEVATABLESTORAGE CABINET 5 Sheets-Sheet 2 Filed Aug. 20, 1964 Q\ m x m F wwe Nm m21M M R h w .1 m T M RA IM A Q. i m ma film- MN. m um a 0 m? a n? QM. P0[-UIH g) @NPF \h QM w w r F F LT F F F F F J r r n K F F x F 4 xx 2 F FF F I a F F F .W F

A ril 12, 1966 A. R. BARTLETT 3,245,741

DESK HAVING ELEVATABLE STORAGE CABINET Filed Aug. 20, 1964 5Sheets-Sheet 3 a: M Nu. lhh

www .4 fi k.

A 7' TORI/E75 April 12, 1966 A. R. BARTLETT 3,245,741

DESK HAVING ELEVAI'ABLE STORAGE CABINET Filed Aug. 20, 1964 5Sheets-Sheet 4.

we J 35 4% INVENTOZ MA Jp d3 46 4% HTT'DkA/E Y5.

April 12, 1966 Filed Aug. 20, 1964 A. R. BARTLETT DESK HAVING ELEVATABLESTORAGE CABINET 5 Sheets-Sheet 5 INVENTOR.

A T 702N 7 United States Patent 45,741 DESK HAVING ELEVATABLE STORAGECABINET Allen R. Bartlett, San Carlos, Califi, assignor to The MoslerSafe Company, Hamilton, Ohio, a corporation of New York Filed Aug. 20,1964, Ser. No. 390,925 4 Claims. (Cl. 312223) This is a continuation inpart of my co-pending application, Serial No. 213,291, filed July 20,1962, now abandoned.

This invention relates to a desk having an elevatable cabinet. Moreparticularly, the invention is directed to a desk having a well acrossthe back and a cabinet mounted in that well, the cabinet being adaptedto be elevated to an operative position exposing shelves and storagecompartments and lowered to a position in which its top is substantiallyflush with the top of the desk.

A desk having a cabinet which can be raised to an elevated position inwhich it projects from the rear edge portion of a desk is not anentirely new concept in the desk art, at least insofar as the patentliterature indicates. Such dmks were proposed as early as the 1920s butnone achieved any degree of commercial success. There are perhaps anumber of reasons for the failure of the early prior art desks to gainacceptance. It might be surmised that the principal reason is that thedesks were not useful. The basic idea has unquestionable merit butgiving that idea a practical effect which would result in the creationof a useful and salable desk has been a problem which has eluded thedesigners of such desks. Thus, the desks have been described showing theelevatable cabinet and means for elevating the cabinet but these designsgenerated no interest. While it is not the intention here to explore thepsychology of desk manufacturing and selling, and while it is impossibleto determine with any great accuracy the reasons for past failures ofsuch desks, it is suggested, that prior designs failed to enjoy anycommercial success, were unattractive, cumbersome and dangerous. Theprior designs lacked the creative touch by which that which was notuseful and dangerous could be transformed to that which would beattractive, efficient, and safe. To effect such a transformation, is theobjective of the present invention.

The first step in the creation of the improved desks is to apply motorpower to effect the raising and lowering of the cabinet and to embodythe motor and power transmission structure in the desk in such a way asto conceal the mechanism substantially completely to avoid thecumbersome and unattractive appearance of the desk. The utilization of amotor to raise and lower the cabinet introduces a powerful elementwhich, in the absence of satisfactory controls, makes a dangerousinstrument of such a commonplace device as a desk. The second step then,in the creation of the improved desk, resides in the application of suchcontrols as will eliminate any possibility of danger to the operator andto items on the desk which might inadvertently be in the path ofmovement of the desk.

To the end of achieving the objectives of the invention, I have employeda number of special features in combination. Among these is a specialreversible motor for raising and lowering the cabinet to provideassurance that the cabinet is always under motor power and thereforeunder control. The particular motor selected is also adapted to be usedas a brake which permits instantaneous stopping of the motor and thecabinet unit in emergency situations. Utilization of the motor as abrake also eliminates much complex mechanical structure which wouldotherwise be required to effect braking of the desk.

3,245,741 Patented Apr. 12, 1966 I have also provided a circuit in whichthe simultaneous operation of two well-spaced push button switches 18required to raise or lower the desk cabinet. Thus, the desk operationrequires the deliberate act of the operator using both hands andeliminates any possibility of inadvertently lowering the desk by bumpinga single operating switch.

I also provide a rather close fit between the cabinet and the deskopening. Since there are vertical walls on three sides of the desk,there is no possibility of injury on those sides due to inadvertentlylowering of the desk. On the fourth and open side of the cabinet, thereis a possibility of injury due to the guillotine effect of the deskshelves crushing an object against that edge of the desk top adjacentthe cabinet opening. At that edge of the desk top, I provide a safetybar which operates switches in the motor circuit to brake and reversethe motor for at least a portion of a revolution. Thus, before anycrushing can take place, one of the surfaces necessary for the crushingaction effects the braking of the motor and stopping of the lowering ofthe cabinet.

I have also provided that the safety bar projects into operativeposition only when the cabinet projects above the surface of the desk sothat when the cabinet is lowered, there are no unsightly projections ontop of the desk. Still further, I use those switches which function withthe safety bars as switches to eifect stopping of the motor when thecabinet has reached its lowermost position.

The several objectives of the invention will become more readilyapparent from the following description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a perspective view of a desk constructed in accordance with myinvention,

FIG. 2 is a perspective view similar to that of FIG. 1 but with theelevatable cabinet in the uppermost position,

FIG. 3 is a fragmentary cross sectional view taken generally along line33 of FIG. 2 but with the cabinet partially lowered,

FIG. 4 is a cross sectional view taken along line 44 of FIG. 3,

FIG. 5 is an enlarged fragmentary elevational view, partially insection, illustrating the manner in which the ends of the cables forraising and lowering the cabinet are secured,

FIG. 6 is an enlarged cross sectional view illustrating the safety bar,that cooperates with the elevatable cabinet in its lowermost or hiddenposition,

FIG. 7 is a view similar to that of FIG. 6, but with the cabinetelevated and the safety bar raised or exposed,

FIG. 8 is an elevational view of the safety bar taken in the directionof line 88 of FIG. 6,

FIG. 9 is a cross sectional view taken along line 9-9 of FIG. 4,illustrating the manner in which the guide shoes cooperate with thecabinet, and

FIG. 10 is a circuit diagram of the motor circuit The invention isdirected to a desk 10 which is constructed as a conventional desk havinga top 11 providing a work surface, and drawers 12-16 mounted betweenlegs 17. Slidable work shelves 18 and 19 are located above the drawersand below the work surface 11. A knee well 20 is defined by inner sidewalls 21, which partially support the drawers, and a rear wall 22, thatforms the front wall of a compartment or well that receives anelevatable cabinet 23. A drawer, the width of knee well 20 could beinstalled immediately below the work surface 11 if it is desired withoutinterfering with the principles of the invention. Side walls 24 and arear wall 25 complete the inclosure of the desk.

The storage cabinet 23 has a plurality of conventional divider walls 26and shelves 27 that can be installed in a number of various locations asdictated by the type of paper work or material to be stored. As shown inFIG. 2, the cabinet is divided so as to provide space for referencebooks and a number of shelves for correspondence or the like. With thecabinet 23 located to the rear and in an elevated position, a sufficientdesk top area remains available at the front of the desk for performanceof regular duties.

The work surface 11 has an opening 28 along its rearward edge to receivethe elevatable cabinet 23. It is to be noted that when the cabinet is inits lowermost position, the work surface of the desk is that of aconventional desk except for a minimum gap that outlines the top 29 ofthe elevatable cabinet. A safety bar 30 (shown in FIG. 2, but bestillustrated in FIGS. 4, 6 7 and 8) is located at the forward edge of theelevatable cabinet 23 and is concealed from view by the work surface 11,when the storage cabinet 23 is in its lowermost position but projectsabove that surface when the cabinet is raised.

The elevatable cabinet is offset to the right with respect to thesymmetry of the desk so as to accommodate an electrical power unitmounted on the left side. The power unit 35 is a reversible motor of thetype described in Patent No. 2,847,629 and is connected to a drive shaft36 through a conventional speed reduction unit 37 and a coupler 38. Themotor 35 and speed reducer 37 are bolted or otherwise secured integrallyto a motor mounting bracket 39, which projects upwardly from ahorizontal member of frame 40. The speed reduction unit 37 preventstorque on drive shaft 36 from rotating the armature of the motor andthus serves to hold the cabinet in any elevated position which itattains.

The drive shaft 36 is mounted for rotation in a pair of bearing blocks42 and 43, FIG. 3, secured to the desk frame on each side of theelevatable cabinet 23. A reel 44 is mounted adjacent the coupled end ofthe shaft 36 and locked thereto as by keying or a set screw. The reelhas a divider wall that divides it into an outer section 45 and an innersection 46 so as to wind a pair of cables without entangling them. Anidentical reel 47 is similarly mounted at the opposite end of the shaft36 and has an outer section 48 and an inner section 49.

Each outer section 45 and 48 of the reels 44 and ,47 has one end of awire cable 50 securely fastened therein. Another cable 51 is similarlysecured to each of the inner sections 46 and 49 of the reels 44 and 47.A threaded stud 52 is fixed to the opposite end of each of the cables 50and 51 and is secured to their respective brackets 53 by an adjustablelocknut 54. The brackets 53 are welded one at each corner to theunderside of cabinet 23. The cables 50 are looped over pulleys 55 ateach end of the cabinet and adjacent the front edge of the cabinet. Thecables 51 are looped over pulleys 56 similarly located at each end andadjacent the rear edge of the cabinet. Pulleys 55 and 56 are mounted forrotation in an inverted U shaped bracket 57 depending from a top supportchannel 58 that extends transversely at each end of the opening 28.

A cylindrical vertical way 60 is located at each end of the cabinet 23and near the rear thereof. The vertical way 60 is anchored at itsuppermost end to the outer leg of channel 58 by a pin 61. At the lowerend, the way 60 is seated upon a bracket 62 projecting from the frame46. A bolt 63 is inserted through an aperture in bracket 62 and threadedinto a hole in the lower end of the way 60). A bearing, mounted injournal block 64, surrounds the vertical way 60 and is securely fastenedto an upstanding flange of the rear brackets 53 by bolts 66. It is to benoted that the brackets 53 bearing journal 64 and their relativecomponents all depend below the under surface of the cabinet 11 so as topermit the complete exposure of the cabinet above the top surface 11 ofthe desk without the display of unsightly hardware. A horizontalenclosing channel 67 is mounted to the bottom of the frame 41 011 eachside. These channels cover the rotating parts of the desk and thuspreclude the danger of clothing or the like being inadvertently wrappedinto them.

As mentioned above, the top surface 29 of the cabinet 23 serves toenlarge the work area when it is in its lowered position. However, ifthe cables 50 and 51 were the only support at this time a slight rockingmotion would occur that would be undesirable. To provide a solid basefor the cabinet, four adjustable screws 68 are located below the cornersof the cabinet 23 and adjusted so that the cabinet 23 will rest on themwhen in its lowermost position.

Referring to FIGS. 5 and 9, each vertical corner of the cabinet 23 isformed by a stainless steel angle 70. Nylon grommets or guide shoes 71are pressed into apertures in the top support channel 50. Guide shoes 71are also pressed into apertures in vertical channel 72 at the front anda similar vertical channel 73 at the rear. These shoes frictionallyengage the flanges of the stainless steel angles 70 to guide and providelateral support for the cabinet as it is raised and lowered. Thisengagement is in both transverse and longitudinal directions and, inaddition to the support given by the vertical ways 60, is suflicient toretain the storage area in vertical alignment at all times.

A normally closed upper limit switch 75 is mounted on a bracket 76depending from the channel 58. An adjustable trip screw 77 is threadedinto a flange 78 of the bracket 65. The trip screw 77 depresses an arm79 of the switch 75 to shut off the power to the drive unit 35 when thecabinet has reached its upper-most position.

Referring to FIGS. 4 and 6-8, the safety bar 30 is mounted for verticalmovement on a bracket 82 depending from the under surface of the desk atthe front of the cabinet 23. Three vertical slots 83 are stamped orotherwise formed at the ends and center of a fiat vertical portion 84 ofthe safety bar 30. Shoulder screws 85 are inserted into the slots 83 andthrough apertures in the bracket 82 and are secured in place by locknuts86. A shank 87 of the screw 85 is of a length that is slightly more thanthe thickness of bracket 82 and safety bar 30, thus when the locknuts 86are tightened against the shoulder a clearance is maintained between thesafety bar 30 and bracket 82 permits the safety bar to slide verticallywith respect to the bracket 82. A pair of lower limit switches 89 and90,- one at each end of the opening 28, are secured to mounting plates91 that are suspended from the bracket 82. The two switches are employedto provide assurance of braking of the motor even though only one sideof the bar 30 is depressed. An actuator 92 of each switch 89 and isspring urged upwardly and into contact with a ledge 93 that projects ata right angle to the safety bar 30.-

A horizontal portion 94 joins an upstanding safety strip 95 to theslidable vertical mounting portion 84. A plurality of fingers 96protrude from the strip 95 and izrgto the path of an overhanging ledge97 of the cabinet As the cabinet is raised, ledge 97 rises permittingfinger 96 to rise until slot 83 abuts the lower side of the shoulderscrew 85 and thus the actuator 92 is permitted to be raised by itsspring (FIG. 7). Additionally, as the cabinet is lowered, ledge 97 comesinto contact with finger 96, as the cabinet reaches its lowermostposition, thus forcing ledge 92 to compress the spring of actuator 92 tobrake the motor 35.

Referring again to FIG. 7, it can be appreciated that if a foreignobject were resting on strip 95 of the safety bar 30, the ledge 97 wouldcome into contact with it on the downward travel of the cabinet and thuswould brake the power unit in the identical manner described above, butbefore the foreign object could be collapsed by the ledge 97. Actually,the motor is not only braked but -is slightly reversed as will bedescribed below.

A series of switches are placed on the front of the desk so as to insurethat the operator will need both hands to raise or lower the cabinet.Switch 98 located on the left is a common safety switch in that it isnecessary to depress it for both raising or lowering of the cabinet. Atthe right side of the desk is an elevating switch 99 and a loweringswitch 100. Thus to elevate the cabinet 23, the switch 98 is depressedsimultaneously with the depressing of switch 99 and completes a circuitto the motor 35. Motor 35 rotates shaft 36 and with it the reels 44 and47 that wind up the cables 50 and 51. As the cables are wound upon thereels, the unwound length is shortened, or otherwise expressed, thestuds 52 are pulled upwardly toward the pulleys 55 and 56 until suchtime as the trip screw 77 engages arm 79 to open switch 75 and brake themotor. To lower the cabinet, switches 97 and 100 must be depressedsimultaneously. Depression of these switches completes a circuit to themotor 35 that causes it to rotate to unwind the cables 50 and 51 fromreels 44 and 47. As the cables unwind, they are kept taut by the weightof the cabinet. Otherwise expressed, the cabinet is simply permitted tolower as fast as the cables are unwound. The motor is braked by theledge 93 of the safety bar 30 engaging the actuator 92 of the switch 90as described above. I

As indicated above, the motor 35 is of the type described in Patent No.2,847,629. The motor and its operation are Well enough described in thatpatent that no detailed description is required here. The motor is asplit phase capacitor start type having an up winding 110 and a downwinding 111, a capacitor 112 and a centrifugal switch 113. The motor hasa rotation sensing switch 114 which swings to the left as viewed in FIG.when the motor is turning to lower the cabinet and swings to the rightwhen the motor is rotating in 'a direction to raise the cabinet. Themotor is ope-rated by a source of alternating current 115 which isselectively connected either'to the up winding 110 or the down winding111 by the manual switches 98, 99 and 100. These switches are doublethrow switches which are shown in their normal position and are springurged to that position. It will be observed that the up Winding can beenergized only when the up switch 99 and the common switch 98 aresimultaneously operated. Similarly, the down winding 111 can beenergized only when the down switch 100 and the common safety switch 98are operated simultaneously. As indicatedin FIG. 2, this operation cantake place only by two hands of the operating person applied to thecommon switches and either the up or down switch which, as shown in FIG.2, are spaced widely apart.

The movement of the cabinet can be stopped by release of either of thehand-held switches. On the other hand, the switches can be held untilthe cabinet moves to its extreme upper or lower position and when thatposition is attained, the motor will be automatically stopped.

In the operation of the motor to move the cabinet in an upward directionthe up winding 110 is energized from the source 115 which is connectedto the winding 110 through the up limit switch 75 in addition to themanual switches 98 and 99. When the up limit switch 75 is contacted bythe trip screw 77 projecting from the cabinet, the circuit connectingthe power source to the winding 110 is interrupted and the limit switch75, swinging to the other contact, connects the winding 111 and thecapacitor 112 in shunt across them) winding 110 to effect dynamicregenerative braking. This regenerative braking is rapid enough for thepurpose of stopping the cabinet when it is moving in an upwarddirection.

When stopping the cabinet when it is moving in a downward direction, amore rapid braking is required particularly in view of the fact that thebraking is required in those emergency situations in which the safetybar has been depressed to operate the limit switches. end, the inventionemploys the instant reversing feature To this of the motor. Thus, wheneither limit switch 89 or is depressed, the power to the winding will bechanged from a normal energization of the down winding 111 to anenergization of the up and down windings 110 and 111 in parallel, withthe down winding being connected in series with the capacitor 112. It isthis connection of windings which provides maximum torque in the updirection not only for immediately braking the motor but also for areversal of the direction of the motor through one or two revolutions.As soon as the rotation sensing switch 114 detects the reversal of themotor shaft, its contacts shift thereby interrupting the power to themotor. Since the motor is operated through reduction gearing, itreverses to the extent of one or two revolutions and results in nomorethan a 1 turn of the shaft 36 to which the winding reels aremounted.

It can now be appreciated that the utilization of the space at the rearof the desk in no way impairs one from the performance of his duties.Depression of switches 98 and 99 will cause the elevatable cabinet torise from the desk. When the cabinet is in this elevated position, alarge amount of shelf space is available for use. If the work surface isnot of a sufficient size for the task to be performed, depression ofswitches 98 and will cause the cabinet to lower within the desk and cometo rest upon a rigid base. When in this lowered position, the desk topis that of a conventional sized desk with the safety bar being pulleddown so that its upper edge is flush with the top surface of the desk.

Switch 98 is located at a convenient position on the left and switches99 and 100 are similarly located to the right so that the operator needsboth hands to raise or lower the cabinet. However, if an object iswithin the confine of the opening into which the cabinet is to bereceived, the safety bar will provide immediate braking of the motorbefore the object can be crushed.

I claim:

1. A desk comprising,

a base,

a top connected to said base, said top having a rectangular opening,

at least two guide shafts vertically mounted to said top and extendingdownwardly therefrom, said shafts mounted adjacent to different cornersof said top,

a rectangular cabinet having horizontal dimensions generallyco-extensive with said opening in said top,

said cabinet slida'bly secured to said guide shafts by guide bracketssecured to said cabinet and encircling said shaft,

an electric motor mounted to said desk, said motor having two drivingdirections,

an output shaft operably connected to said motor and rotated thereby,

a plurality of pulleys, at least four of which are axially secured tosaid output shaft, and rotatable therewith, and at least four of whichare secured to the base of said desk above said output shaft,

said pulleys being axially rotatable in a vertical plane,

a plurality of cable receiving brackets mounted to said cabinet at abottom corner thereof,

said cables each passing over a pulley mounted to said base so thatrotation of said output shaft in a first direction 'winds said cablesaround said pulleys and raises said cabinet and a subsequent rotation inan opposite direction unwinds said cables from said pulleys and lowerssaid cabinet,

an electrical raising switch mounted to said base and operably connectedto said motor for actuation thereof in said first and oppositedirections,

an electrical limiting switch mounted to said base for halting theupward movement of said cabinet,

abutment means on said cabinet engageable with and actuating saidlimiting switch so that when said cabinet carries said abutment meansinto engagement with said limiting switch, said switch is actuated andthe upward movement of said shelf is halted,

at least one down limit switch mounted to and below said top adjacent tothe front of said opening, said switch halting the downward movement ofsaid shelf when actuated,

an actuator bar operably connected to said down switch said bar beingspring biased and extending beyond the plane of said top when said shelfis moved upwardly above said top,

said bar when depressed actuating said down switch and halting downwardmovement of said shelf,

and means on said cabinet for engaging and operating said down switchwhen said cabinet has attained its lowermost position.

2. A desk comprising,

a base,

a top connected to said base, said top having a rectangular opening,

a rectangular cabinet having horizontal dimensions generally coextensivewith said opening in said top, said cabinet slidably secured to saidguide shafts by guide brackets secured to said cabinet and encirclingsaid shaft,

an electric motor mounted to said desk, said motor having two drivingdirections,

an output shaft operably connected to said motor and rotated thereby,

a plurality of pulleys, at least four of which are axially secured tosaid output shaft, and rotatable therewith, and at least four of whichare secured to the base of said desk above said output shaft,

said pulleys being axially rotatable in a vertical plane,

a plurality of cable receiving brackets mounted to said cabinet at abottom corner thereof,

a plurality of cables each secured at one end to a pulley mounted onsaid output shaft and secured at the other end to a cable receivingbracket,

said cables each passing over a pulley mounted to said base so thatrotation of said output shaft in a first direction winds said cablesaround said pulleys and raises said cabinet and rotation in an oppositedirection unwinds said cables from said pulleys and lowers said cabinet,

switch means mounted to said base and operably connected to said motorfor actuation thereof in said first and opposite directions,

a control switch widely spaced from said switch means and interconnected'with said switch means whereby both said switch means and said controlswitch must be activated to effect either raising or lowering of saidcabinet,

anelectrical limiting switch mounted to said base for halting the upwardmovement of said cabinet,

abutment means on said cabinet engageable with and actuating saidlimiting switch so that when said cabinet carries said abutment meansinto engagement with said limiting switch, said switch is actuated andthe upward movement of said shelf is halted,

at least two electric safety switches mounted to and below said topadjacent to the front of said opening, said switches halting thedownward movement of said shelf when depressed,

an actuator bar operably connected to said safety switches, said barbeing spring biased and extending beyond the plane of said top when saidshelf is moved upwardly above said top,

said bar when depressed actuating said safety switch and haltingdownward movement of said shelf.

3. A desk comprising,

a base,

a top connected to said base, said top having a rectangular opening,

a rectangular cabinet having horizontal dimensions generally coextensivewith said opening in said top,

an electric motor mounted to said desk, said motor having two drivingdirections,

means connecting said motor to said cabinet to raise and lower same,

an electrical raising switch mounted to said base and operably connectedto said motor for actuation thereof in said first and oppositedirections,

an electrical limited switch mounted to said base for halting the upwardmovement of said cabinet,

abutment means on said cabinet engageable with and actuating saidlimited switch so that when said cabinet carries said abutment meansinto engagement with said limited switch, said switch is actuated andthe upward movement of said cabinet is halted,

at least one down limit switch mounted to and below said top adjacent tothe front of saidopening, said switch halting the downward movement ofsaid cabinet when actuated,-

an actuator bar operably connected to said down switch, said bar beingspring biased andextending beyond the plane of said top when saidcabinet is moved up wardly above said top,

said bar when depressed at least to the level of said top actuating saiddown switch to halt downward movement of said shelf.

4. A desk comprising,

a base,

a top connected to said base, said top having a rectangular opening,

at least two guide shafts vertically mounted to said top and extendingdownwardly therefrom, said shafts mounted adjacent to different cornersof said top,

a rectangular cabinet having horizontal dimensions generallyco-extensive with said opening in said top,

said cabinet slidably secured to said guide shafts by guide bracketssecured to said cabinet and encircling said shaft,

an electric motor mounted to said desk, said motor having two drivingdirections,

an output shaft operably connected to said motor and rotated thereby,

a plurality of pulleys, at least four of which are axially secured tosaid output shaft, and rotatable therewith, and at least four of whichare secured to the base of said desk above said output shaft,

said pulleys being axially rotatable in a vertical plane,

a plurality of cables each secured at one end to a pulley mounted onsaid output shaft and secured at the other end to said cabinet,

a plurality of cables each secured at one end to a pulley mounted onsaid output shaft and secured at the otherend to a cable receivingbracket,

said cables each passing over a pulley mounted to said base so thatrotation of said output shaft in a first direction winds said cablesaround said pulleys and raises said cabinet and a subsequent rotation inan opposite direction unwindssaid cables from said pulleys and lowerssaid cabinet,

an electrical raising switch means mounted to said base and operablyconnected to said motor for actuation thereof in said first and oppositedirections,

an electric limiting switch mounted to said base for halting the upwardmovement'of said cabinet,

abutment means on said cabinet engageable with and actuating saidlimiting switch so that when said cabinet carries said abutment meansinto engagement with said limiting switch, said switch is actuated andthe upward movement of said shelf is halted,

at least two electric safety switches mounted to and below said topadjacent to the front of said opening, said switches halting thedownward movement of said shelf when depressed,

an actuator bar operably connected to said safety switches, said barbeing spring biased and extending beyond the plane of said top when saidshelf is moved upwardly above said top,

9 10 said bar when depressed actuating said safety switch 2,861,857 11/1958 Lee 312223 and halting downward movement of said shelf. 2,875,0122/ 1959 Riley 312223 2,895,311 7/1959 Spalvins 3123 12 X ReferencesCited by the Examiner UN STATES A 5 CLAUDE A. LE ROY, Primary Examiner..1,247,590 11/ 1917 Sprung 312-312 CHAN CELLOR E. HARRIS, FRANK B.SHERRY, 1,990,300 2/1935 Miller 3123 12 X Examiners.

2,758,901 8/1956 Cole 312-223

1. A DESK COMPRISING, A BASE, A TOP CONNECTED TO SAID BASE, SAID TOPHAVING A RECTANGULAR OPENING, AT LEAST TWO GUIDE SHAFTS VERTICALLYMOUNTED TO SAID TOP AND EXTENDING DOWNWARDLY THEREFROM, SAID SHAFTSMOUNTED ADJACENT TO DIFFERENT CORNERS OF SAID TOP, A RECTANGULAR CABINETHAVING HORIZONTAL DIMENSIONS GENERALLY CO-EXTENSIVE WITH SAID OPENING INSAID TOP, SAID CABINET SLIDABLY SECURED TO SAID GUIDE SHAFTS BY GUIDEBRACKETS SECURED TO SAID CABINET AND ENCIRCLING SAID SHAFT, AN ELECTRICMOTOR MOUNTED TO SAID DESK, SAID MOTOR HAVING TWO DRIVING DIRECTIONS, ANOUTPUT SHAFT OPERABLY CONNECTED TO SAID MOTOR AND ROTATED THEREBY, APLURALITY OF PULLEYS, AT LEAST FOUR OF WHICH ARE AXIALLY SECURED TO SAIDOUTPUT SHAFT, AND ROTATABLE THEREWITH, AND AT LEAST FOUR OF WHICH ARESECURED TO THE BASE OF SAID DESK ABOVE SAID OUTPUT SHAFT, SAID PULLEYSBEING AXIALLY ROTATABLE IN A VERTICAL PLANE, A PLURALITY OF CABLERECEIVING BRACKETS MOUNTED TO SAID CABINET AT A BOTTOM CORNER THEREOF,SAID CABLES EACH PASSING OVER A PULLEY MOUNTED TO SAID BASE SO THATROTATION OF SAID OUTPUT SHAFT IN A FIRST DIRECTION WINDS SAID CABLESAROUND SAID PULLEYS AND RAISES SAID CABINET AND A SUBSEQUENT ROTATION INAN OPPOSITE DIRECTION UNWINDS SAID CABLES FROM SAID PULLEYS AND LOWERSSAID CABINET, AN ELECTRICAL RAISING SWITCH MOUNTED TO SAID BASE ANDOPERABLY CONNECTED TO SAID MOTOR FOR ACTUATION THEREOF IN SAID FIRST ANDOPPOSITE DIRECTIONS, AN ELECTRICAL LIMITING SWITCH MOUNTED TO SAID BASEFOR HALTING THE UPWARD MOVEMENT OF SAID CABINET, ABUTMENT MEANS ON SAIDCABINET ENGAGEABLE WITH AND ACTUATING SAID LIMITING SWITCH SO THAT WHENSAID CABINET CARRIES SAID ABUTMENT MEANS INTO ENGAGEMENT WITH SAIDLIMITING SWITCH, SAID SWITCH IS ACTUATED AND THE UPWARD MOVEMENT OF SAIDSHELF IS HALTED, AT LEAST ONE DOWN LIMIT SWITCH MOUNTED TO AND BELOWSAID TOP ADJACENT TO THE FRONT OF SAID OPENING, SAID SWITCH HALING THEDOWNWARD MOVEMENT OF SAID SHELF WHEN ACTUATED, AN ACTUATOR BAR OPERABLYCONNECTED TO SAID DOWN SWITCH SAID BAR BEING SPRING BIASED AND EXTENDINGBEYOND THE PLANE OF SAID TOP WHEN SAID SHELF IS MOVED UPWARDLY ABOVESAID TOP, SAID BAR WHEN DEPRESSED ACTUATING SAID DOWN SWITCH AND HALTINGDOWNWARD MOVEMENT OF SAID SHELF, AND MEANS ON SAID CABINET FOR ENGAGINGAND OPERATING SAID DOWN SWITCH WHEN SAID CABINET HAS ATTAINED ITSLOWERMOST POSITION.